Display device and method of manufacturing the same

ABSTRACT

A display device includes: a substrate; a display element layer on one surface of the substrate and including at least one light emitting element emitting light; and a pixel circuit portion on the display element layer and including at least one transistor electrically connected to the light emitting element, wherein the display element layer includes: a first electrode on the substrate and electrically connected to one end of the light emitting element; a second electrode on the substrate and electrically connected to the other end of the light emitting element; and an insulation layer on the substrate including the second electrode, and having a first opening exposing a portion of the second electrode, and wherein the second electrode is electrically connected to the transistor through the first opening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/214,786, filed Dec. 10, 2018, which claims priority to and thebenefit of Korean Patent Application No. 10-2018-0015897, filed Feb. 8,2018, the entire content of both of which is incorporated herein byreference.

BACKGROUND 1. Field

Aspects of some example embodiments relate to a display device and amethod of manufacturing the same.

2. Discussion of Related Art

Light emitting diodes (hereinafter referred to as LEDs) exhibitrelatively good durability even under adverse environmental conditionsand have excellent performance in terms of lifetime and luminance.

In recent years, research for applying such LEDs to various displaydevices has been actively conducted.

As a part of this research, a technique for manufacturing ultra-smallrod-like LEDs, such as on a microscale or a nanoscale, using aninorganic crystal structure, for example, a structure where anitride-based semiconductor is grown is being developed. For example,the rod-like LEDs may be manufactured to a small size enough toconstitute a pixel or the like of a self-emission display device.

The above information disclosed in this Background section is only forenhancement of understanding of the background and therefore it maycontain information that does not constitute prior art.

SUMMARY

One or more embodiments include a display device and a method ofmanufacturing the same which may prevent or reduce defects of thedisplay device.

According to some embodiments, a display device may include a substrate;a display element layer disposed on one surface of the substrate andincluding at least one light emitting element emitting light; and apixel circuit portion disposed on the display element layer andincluding at least one transistor electrically connected to the lightemitting element, wherein the display element layer includes: a firstelectrode on the substrate and electrically connected to one end of thelight emitting element; a second electrode on the substrate andelectrically connected to the other end of the light emitting element;and an insulation layer on the substrate including the second electrodeand having a first opening exposing a portion of the second electrode,and wherein the second electrode is electrically connected to thetransistor through the first opening.

The display element layer may further include a first conductiveelectrode disposed adjacent to the one end of the light emitting elementand a second conductive electrode disposed adjacent to the other end ofthe light emitting element, and the first conductive electrode and thesecond conductive electrode may be spaced apart from each other with thelight emitting element interposed therebetween.

The first conductive electrode may include a cathode electrode and thesecond conductive electrode may include an anode electrode.

The first electrode may be on the first conductive electrode and the oneend of the light emitting element and may electrically connect the firstconductive electrode and the one end of the light emitting element, andthe second electrode may be on the second conductive electrode and theother end of the light emitting element and may electrically connect thesecond conductive electrode and the other end of the light emittingelement.

The insulation layer may include a first insulation layer on the secondelectrode and a second insulation layer on the first insulation layer toflatten a surface of the first insulation layer. In addition, the firstopening may penetrate through the first and second insulation layers toexpose the portion of the second electrode. In addition, the insulationlayer may further include a second opening exposing a portion of thefirst electrode. The second opening may penetrate through the first andsecond insulation layers to expose the portion of the first electrode.

The transistor may include a semiconductor layer disposed on the secondinsulation layer, a gate electrode disposed on the semiconductor layerwith a first gate insulation layer interposed therebetween, and sourceand drain electrodes connected to the semiconductor layer. In addition,the drain electrode may include a first portion connected to thesemiconductor layer and a second portion connected to the secondelectrode through the second opening.

The drain electrode may be disposed on the gate electrode with a secondgate insulation layer interposed therebetween and the source electrodemay be disposed on the drain electrode with an interlayer insulatinglayer interposed therebetween.

The second electrode may be a reflective electrode that reflects thelight emitted from the light emitting element toward the other surfaceof the substrate.

The display device may further comprise a polarizing film disposed onthe other surface of the substrate.

The display device may further comprise a reflective electrode disposedbetween the one surface of the substrate and the display element layer.

The reflective electrode may reflect the light emitted from the lightemitting element toward the one surface of the substrate.

The display device may further comprise a polarizing film disposed onthe pixel circuit portion.

The pixel circuit portion may include a driving voltage line disposed onthe first gate insulation layer, and a bridge pattern disposed on thesecond gate insulation layer and electrically connected to the drivingvoltage line and the first electrode.

The bridge pattern may include a first bridge pattern connected to thefirst electrode through the second opening and a second bridge patternconnected to the driving voltage line. In addition, the first bridgepattern and the second bridge pattern may be integrally provided.

The first electrode may be electrically connected to the driving voltageline through the bridge pattern.

The light emitting element may include a light emitting diode in theform of a cylindrical column or a polygonal column having a microscaleor a nanoscale size.

According to some embodiments, a method of manufacturing the displaydevice may include providing a substrate; forming a display elementlayer including at least one light emitting element emitting light onone surface of the substrate; and forming a pixel circuit portionincluding at least one transistor electrically connected to the lightemitting element on the display element layer, wherein the forming thedisplay element layer comprises: forming a first conductive electrodeand a second conductive electrode spaced apart from the first electrodeon the one surface of the substrate; self-aligning the light emittingelement on the one surface of the substrate by supplying power to thefirst conductive electrode and the second conductive electrode,respectively; forming a first electrode electrically connecting one endof the light emitting element and the first conductive electrode;forming a second electrode electrically connecting the other end of thelight emitting element and the second conductive electrode; and formingan insulating material layer on the second electrode to cover the secondelectrode.

The method may further include ohmic contacting the first electrode andthe one end of the light emitting element by heat-treating an interfacebetween the first electrode and the one end of the light emittingelement by using a rapid thermal annealing (RTA) method; and ohmiccontacting the second electrode and the other end of the light emittingelement by heat-treating an interface between the second electrode andthe other end of the light emitting element by using a rapid thermalannealing (RTA) method.

The first electrode may include a cathode electrode and the secondelectrode may include an anode electrode.

The second electrode may be a reflective electrode that reflects thelight emitted from the light emitting element toward the other surfaceof the substrate.

The method further include forming a polarizing film on the othersurface of the substrate.

The method may further include forming a reflective electrode betweenthe one surface of the substrate and the display element layer.

The method may further include forming a polarizing film on the pixelcircuit portion.

The providing the pixel circuit portion may include forming asemiconductor layer including a source region, a channel region, and adrain region on the insulating material layer; forming a first gateinsulating material layer on the semiconductor layer; forming a gateelectrode and a driving voltage line on the first gate insulatingmaterial layer; forming a second gate insulating material layer on thegate electrode and the driving voltage line; etching the second gateinsulating material layer to expose a portion of the driving voltageline, etching the first and second gate insulating material layers toform a contact hole exposing the drain region, and simultaneouslyetching the first and second gate insulating material layers and theinsulating material layer to form first and second openings exposingportions of the first and second electrodes, respectively; forming abridge pattern connected to an exposed driving voltage line and thefirst electrode and a drain electrode connected to an exposed drainregion and the second electrode; forming an interlayer insulatingmaterial layer on the substrate including the bridge pattern and thedrain electrode; etching the interlayer insulating material layer, thesecond gate insulating material layer, and the first gate insulatingmaterial layer to form an interlayer insulation layer exposing thesource region, a second gate insulation layer, and a first gateinsulation layer; and forming a source electrode connected to the sourceregion.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the inventive concepts, and are incorporated in andconstitute a part of this specification, illustrate aspects of exampleembodiments of the inventive concepts, and, together with thedescription, serve to explain aspects of some principles of theinventive concepts.

FIG. 1 is a perspective view illustrating a rod-like light emittingdiode according to some example embodiments of the invention.

FIG. 2 is a plan view illustrating a unit light emitting region of alight emitting device including the rod-like light emitting diode shownin FIG. 1.

FIG. 3 is a cross-sectional view taken along the line I-I′ of FIG. 2.

FIG. 4 is a schematic plan view of a display device according to anembodiment of the invention for illustrating, in particular, the displaydevice using the rod-like LED shown in FIG. 1 as a light emittingsource.

FIG. 5 is a cross-sectional view illustrating a portion of the displaydevice shown in FIG. 4.

FIGS. 6 to 17 are cross-sectional views sequentially illustrating amethod of manufacturing the display device shown in FIG. 5.

FIG. 18 is a cross-sectional view illustrating a display deviceaccording to some example embodiments of the invention.

DETAILED DESCRIPTION

Reference will now be made in detail to various embodiments of thepresent disclosure, specific examples of which are illustrated in theaccompanying drawings and described below, because the embodiments ofthe present disclosure may be variously modified in many differentforms. However, this is not intended to limit the present disclosure toparticular modes of practice, and it is to be appreciated that allchanges, equivalents, and substitutes that do not depart from the spiritand technical scope of the present disclosure are encompassed in thepresent disclosure.

Throughout the disclosure, like reference numerals refer to like partsthroughout the various figures and embodiments of the presentdisclosure. The sizes of elements in the accompanying drawings may beexaggerated for clarity of illustration. It will be understood that,although the terms “first”, “second”, etc. may be used herein todescribe various elements, these elements should not be limited by theseterms. These terms are only used to distinguish one element from anotherelement. For instance, a first element discussed below could be termed asecond element without departing from the teachings of the presentdisclosure. Similarly, the second element could also be termed the firstelement. In the present disclosure, the singular forms are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise.

It will be further understood that the terms “comprise”, “include”,“have”, etc. when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, components,and/or combinations of them but do not preclude the presence or additionof one or more other features, integers, steps, operations, elements,components, and/or combinations thereof. Furthermore, when a first partsuch as a layer, a film, a region, or a plate is disposed on a secondpart, the first part may be not only directly on the second part but athird part may intervene between them. In addition, when it is expressedthat a first part such as a layer, a film, a region, or a plate isformed on a second part, the surface of the second part on which thefirst part is formed is not limited to an upper surface of the secondpart but may include other surfaces such as a side surface or a lowersurface of the second part. To the contrary, when a first part such as alayer, a film, a region, or a plate is under a second part, the firstpart may be not only directly under the second part but a third part mayintervene between them.

Hereinafter, aspects of some example embodiments of the presentinvention will be described in more detail with reference to theaccompanying drawings.

FIG. 1 is a perspective view illustrating a rod-like light emittingdiode according to some example embodiments of the invention. In FIG. 1,a rod-like light emitting diode LD in the form of a cylindrical columnis shown, but the invention is not limited thereto.

Referring to FIG. 1, the rod-like light emitting diode LD according tosome example embodiments of the invention may include a first conductivesemiconductor layer 11, a second conductive semiconductor layer 13, andan active layer 12 positioned between the first conductive semiconductorlayer 11 and the second conductive semiconductor layer 13. For example,the rod-like light emitting diode LD may be formed as a laminate inwhich the first conductive semiconductor layer 11, the active layer 12,and the second conductive semiconductor layer 13 are sequentiallystacked. In the following embodiments, the rod-like light emitting diodeLD is referred to as “a rod-like LED LD”.

According to some example embodiments of the invention, the rod-like LEDLD may be provided in a rod shape extending along one direction. When anextension direction of the rod-like LED LD is a longitudinal direction,the rod-like LED LD may have one end and the other end along theextension direction. According to some example embodiments of theinvention, one of the first conductive semiconductor layer 11 and thesecond conductive semiconductor layer 13 may be positioned at the oneend of the rod-like LED LD and the other one of the first conductivesemiconductor layer 11 and the second conductive semiconductor layer 13may be positioned at the other end thereof.

In FIG. 1, the rod-like LED LD may be provided in a cylindrical columnshape, but embodiments of the present invention are not limited thereto.The term “rod-like” may include a rod or bar shape extending along thelongitudinal direction and having an aspect ratio greater than 1 such asa cylindrical column, a polygonal column, or the like. For example, thelength of the rod-like LED LD may be greater than the diameter thereof.

For example, the rod-like LED LD may be manufactured to a small size tohave a diameter and/or length on the order of microscale or a nanoscale.The size of the rod-like LED LD according to some example embodiments ofthe present invention are not limited thereto and may be changed to meetthe requirements of a display device to which the rod-like LED LD isapplied.

The first conductive semiconductor layer 11 may include at least onen-type semiconductor layer. For example, the first conductivesemiconductor layer 11 may include one of the semiconductor materials ofInAlGaN, GaN, AlGaN, InGaN, AlN, InN, and the like and may be doped witha first conductive dopant such as Si, Ge, Sn, and the like. However, thematerials of the first conductive semiconductor layer 11 are not limitedthereto. The first conductive semiconductor layer 11 may include variousother materials not described herein.

The active layer 12 may be disposed on the first conductivesemiconductor layer 11 and may have a single or multiple quantum wellstructure. The active layer 12 may include AlGaN, InAlGaN, or the like.

According to some example embodiments of the present invention, acladding layer doped with a conductive dopant may be positioned on anupper portion and/or a lower portion of the active layer 12. Thecladding layer may include AlGaN, InAlGaN, or the like.

When an electric field exceeding a voltage (e.g., a predeterminedvoltage) is applied to both ends of the rod-like LED LD, electron-holepairs are generated in the active layer 12, so that the rod-like LED LDemits light.

The second conductive semiconductor layer 13 may be provided on theactive layer 12 and may include a semiconductor layer of a differenttype from the first conductive semiconductor layer 11. The secondconductive semiconductor layer 13 may include at least one p-typesemiconductor layer. The second conductive semiconductor layer 13 mayinclude at least one of the semiconductor materials of InAlGaN, GaN,AlGaN, InGaN, AlN, and InN and may be doped with a second conductivedopant such as Mg, and the like. Material of the second conductivesemiconductor layer 13 is not limited thereto. The second conductivesemiconductor layer 13 may include various other materials not describedherein.

The rod-like LED LD may include at least one of a phosphor layer, anactive layer, a semiconductor layer and/or an electrode layer disposedon an upper and/or lower portion of each of the first conductivesemiconductor layer 11, the active layer 12, and the second conductivesemiconductor layer 13.

In addition, the rod-like LED LD may further include an insulation layer14. The insulation layer 14 may be provided on a portion of the firstconductive semiconductor layer 11, the active layer 12, and the secondconductive semiconductor layer 13. For example, the insulation layer 14may be provided at a portion except for both ends of the rod-like LEDLD, so that both ends of the rod-like LED LD may be exposed.

As illustrated in FIG. 1, a portion of the insulation layer 14 isremoved. But actually, all side surfaces of the road-like LED LD may besurrounded by the insulation layer 14.

The insulation layer 14 may be provided to surround at least a portionof the outer surface of the first conductive semiconductor layer 11, theactive layer 12, and/or the second conductive semiconductor layer 13.For example, the insulation layer 14 may be provided to surround atleast the outer surface of the active layer 12.

The insulation layer 14 may include a transparent insulating material.For example, the insulation layer 14 may include at least one insulatingmaterial selected from the group consisting of SiO₂, Si₃N₄, Al₂O₃ andTiO₂. However, the invention is not limited thereto, and various otherinsulating materials may be used.

When the insulation layer 14 is provided on the rod-like LED LD, it ispossible to prevent the active layer 12 from being short-circuited tofirst and/or second electrodes. In addition, surface defects of therod-like LED LD may be minimized by the insulation layer 14, so thatlifetime and efficiency of the rod-like LED LD may be improved. When aplurality of rod-like LEDs LD are positioned adjacent to each other, theinsulation layer 14 may prevent or reduce instances of unwanted shortsthat may otherwise occur between the rod-like LEDs LD.

The rod-like LED LD may be used as a light emitting source for variousdisplay devices. For example, the rod-like LED LD may be used as a lightemitting source of a lighting device or a self-emission display device.

FIG. 2 is a plan view illustrating a unit light emitting region of alight emitting device including the rod-like light emitting diode shownin FIG. 1. FIG. 3 is a cross-sectional view taken along line I-I′ ofFIG. 2.

For convenience of illustration, although FIG. 2 shows rod-like LEDsaligned in a horizontal direction, the arrangement of the rod-like LEDsis not limited thereto. For example, the rod-like LEDs may be aligned inan oblique direction between the first electrode and the secondelectrode. In addition, in FIG. 2, the unit light emitting region may bea pixel region including one pixel PXL.

Referring to FIGS. 1 to 3, a light emitting device according to anembodiment of the invention may include a substrate SUB, a buffer layerBFL, a plurality of rod-like LEDs LD, a partition wall PW, first andsecond electrodes EL1 and El2, and first and second contact electrodesCNE1 and CNE2.

The substrate SUB may include an insulating material such as glass,organic polymer, quartz, or the like.

The buffer layer BFL may prevent impurities from diffusing into therod-like LEDs LD.

Each of the rod-like LEDs LD may include the first conductivesemiconductor layer 11, the second conductive semiconductor layer 13,and the active layer 12 positioned between the first conductivesemiconductor layer 11 and the second conductive semiconductor layer 13.In addition, when viewed in a first direction DR1, each of the rod-likeLEDs LD may include a first end EP1 and a second end EP2. One of thefirst conductive semiconductor layer 11 and the second conductivesemiconductor layer 13 may be positioned at the first end EP1 and theother one of the first conductive semiconductor layer 11 and the secondconductive semiconductor layer 13 may be positioned at the second endEP2. In an embodiment of the invention, each of the rod-like LEDs LD mayemit light of one of red, green, blue, and white colors.

The rod-like LEDs LD may include a first rod-like LED LD1 arranged onthe left side of the second electrode EL2 and a second rod-like LED LD2arranged on the right side of the second electrode EL2. When viewed in aplan view, the first rod-like LED LD1 and the second rod-like LED LD2may be spaced apart from each other with the second electrode EL2interposed therebetween.

The partition wall PW may be positioned on the substrate SUB and maydefine a light emitting region in the unit light emitting region. Twopartition walls PW adjacent to each other may be spaced apart from eachother by a distance (e.g., a predetermined distance) on the substrateSUB. For example, two adjacent partition walls PW may be spaced apart onthe substrate SUB by the length of each rod-like LED LD or more. Thepartition wall PW may be an insulating material including an inorganicmaterial or an organic material, but is not limited thereto. Thepartition wall PW may include an opening corresponding to the rod-likeLED LD.

A first insulation layer INS1 may be positioned on the substrate SUBincluding the partition wall PW. The first insulation layer INS1 maycover a portion of a top surface of each rod-like LED LD. The first endEP1 and the second end EP2 of each rod-like LED LD may be exposed to theoutside by the first insulation layer INS1.

The first electrode EL1 may be disposed on the partition wall PW. Thefirst electrode EL1 may be positioned adjacent to one end of the firstand second ends EP1 and EP2 of each rod-like LED LD and may beelectrically connected to the corresponding one of the first and secondends EP1 and EP2 by the first contact electrode CNE1.

When viewed in a plan view, the first electrode EU may include a (1-1)thelectrode EL1_1 and a (1-2)th electrode EL1_2 branched to the left andright of the second electrode EL2. Accordingly, the second electrode EL2may be positioned between the (1-1)th electrode EL1_1 and the (1-2)thelectrode EL1_2. The (1-1)th electrode EL1_1 and the (1-2)th electrodeEL1_2 may have a bar shape extending along a second direction DR2intersecting the first direction DR1. The (1-1)th electrode EL1_1 andthe (1-2)th electrode EL1_2 may be connected to each other by a firstconnection line CNL1 extending along the first direction DR1.

The second electrode EL2 may be provided between the first rod-like LEDLD1 and the second rod-like LED LD2 on the substrate SUB. Concretely,the second electrode EL2 may be provide between the second end EP2 ofthe first rod-like LED LD1 and the first end EP1 of the second rod-likeLED LD2 on the substrate SUB. The second electrode EL2 may beelectrically connected to a second connection line CNL2.

One of the first and second electrodes EL1 and EL2 may be an anodeelectrode and the other of the first and second electrodes EU and EL2may be a cathode electrode. In an embodiment of the invention, the firstelectrode EL1 may be a cathode electrode and the second electrode EL2may be an anode electrode.

The first and second electrodes EL1 and EL2 are directly provided on thesubstrate SUB including the partition wall PW in the drawings, but theinvention is not limited thereto. For example, an element for drivingthe light emitting device as an active matrix may further be providedbetween the first and second electrodes EL1 and EL2 and the substrateSUB. When the light emitting device is driven as the active matrix,signal lines, an insulation layer and/or a transistor may be providedbetween the first and second electrodes EU and EL2 and the substrateSUB. The signal lines may include a scan line, a data line, a drivingvoltage line DVL, and the like. The transistor may be connected to thesignal lines and may include a gate electrode, a semiconductor layer, asource electrode, and a drain electrode.

One of the source and drain electrodes of the transistor may beconnected to the second electrode EL2 through the second connection lineCNL2. A data signal of the data line may be applied to the secondelectrode EL2 through the transistor. In addition, the driving voltageline DVL may be connected to the first connection line CNL1 through acontact hole CH and may be connected to the first electrode EL1. Asignal of the driving voltage line DVL may be applied to the firstelectrode EL1 through the first connection line CNL1.

The first electrode EL1, the second electrode EL2, the first connectionline CNL1, and the second connection line CNL2 may include the samematerial. For example, the first electrode EL1, the second electrodeEL2, the first connection line CNL1, and the second connection line CNL2may include a conductive material. The conductive material may include ametal such as Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr or an alloythereof, a conductive oxide such as ITO (indium tin oxide), IZO (indiumzinc oxide), ZnO (zinc oxide) or ITZO (indium tin zinc oxide), aconductive polymer such as PEDOT, or the like. The first electrode EL1,the second electrode EL2, the first connection line CNL1, and the secondconnection line CNL2 may be formed of a single layer, but the inventionis not limited thereto. The first electrode EL1, the second electrodeEL2, the first connection line CNL1, and the second connection line CNL2may be formed of a multilayer in which two or more materials of metals,alloys, conductive oxides and conductive polymers are stacked.

The first contact electrode CNE1 may be disposed on the first electrodeEL1. The first contact electrode CNE1 may include a (1-1)th contactelectrode CNE1_1 and a (1-2)th contact electrode CNE1_2. When viewed ina plan view, the (1-1)th contact electrode CNE1_1 may overlap the firstend EP1 of the first rod-like LED LD1 and the (1-1)th electrode EL1_1.In addition, when viewed in a plan view, the (1-2)th contact electrodeCNE1_2 may overlap the second end EP2 of the second rod-like LED LD2 andthe (1-2)th electrode EL1_2.

A second insulation layer INS2 may be positioned on the first contactelectrode CNE1 to cover the first contact electrode CNE1.

The second contact electrode CNE2 may be positioned on the secondelectrode EL2. When viewed in a plan view, the second contact electrodeCNE2 may cover the second electrode EL2 and overlap the second electrodeEL2. In addition, the second contact electrode CNE2 may partiallyoverlap the second end EP2 of the first rod-like LED LD1 and the firstend EP1 of the second rod-like LED LD2.

A third insulation layer INS3 may be positioned on the second contactelectrode CNE2 to cover the second contact electrode CNE2. The thirdinsulation layer INS3 prevents the second contact electrode CNE2 frombeing exposed to the outside, so that corrosion of the second contactelectrode CNE2 may be prevented or reduced. The third insulation layerINS3 may include one of an inorganic insulating material and an organicinsulating material.

An overcoat layer OC may be positioned on the third insulation layerINS3. The overcoat layer OC may be a planarization layer that serves toflatten the surface roughened by the underlying components. In addition,the overcoat layer OC may be an encapsulating layer that prevents orreduces instances of oxygen and moisture penetrating into the rod-likeLEDs LD.

As described above, the first end EP1 of the first rod-like LED LD1 maycontact the (1-1)th electrode EL1_1 and the second end EP2 of the firstrod-like LED LD1 may contact one side of the second electrode EL2. Forexample, the first conductive semiconductor layer 11 of the firstrod-like LED LD1 may contact the (1-1)th electrode EL1_1 and the secondconductive semiconductor layer 13 of the first rod-like LED LD1 maycontact the one side of the second electrode EL2. Therefore, the firstand second conductive semiconductor layers 11 and 13 of the firstrod-like LED LD1 may receive a voltage (e.g., a predetermined voltage)through the (1-1)th electrode EL1_1 and the second electrode EL2. Whenan electric field exceeding the voltage (e.g., the predeterminedvoltage) is applied to the first and second ends EP1 and EP2 of thefirst rod-like LED LD1, the first rod-like LED LD1 emits light while theelectron-hole pairs are generated in the active layer 12.

In addition, the first end EP1 of the second rod-like LED LD2 maycontact the other side of the second electrode EL2 and the second endEP2 of the second rod-like LED LD2 may contact the (1-2)th electrodeEL1_2. For example, the first conductive semiconductor layer 11 of thesecond rod-like LED LD2 may contact the (1-2)th electrode EL1_2 and thesecond conductive semiconductor layer 13 of the second rod-like LED LD2may contact the other side of the second electrode EL2. Therefore, thefirst and second conductive semiconductor layers 11 and 13 of the secondrod-like LED LD2 may receive a voltage (e.g., a predetermined voltage)through the (1-2)th electrode EL1_2 and the second electrode EL2. Whenan electric field exceeding the voltage (e.g., the predeterminedvoltage) is applied to the first and second ends EP1 and EP2 of thesecond rod-like LED LD2, the second rod-like LED LD2 emits light whilethe electron-hole pairs are generated in the active layer 12.

FIG. 4 is a schematic plan view of a display device according to someexample embodiments of the invention for illustrating, for example, thedisplay device using the rod-like LED shown in FIG. 1 as a lightemitting source.

Referring to FIGS. 1 and 4, the display device according to some exampleembodiments of the present invention may include the substrate SUB,pixels PXL provided on one surface of the substrate SUB, a driving unitprovided on the substrate SUB to drive the pixels PXL, and a lineportion for connecting the pixels PXL and the driving unit.

The substrate SUB may include a display region DA and a non-displayregion NDA. The display region DA may be a region where the pixels PXLfor displaying an image are provided. The non-display region NDA may bea region where the driving unit for driving the pixels PXL and a portionof the line portion for connecting the pixels PXL and the driving unitare provided.

The pixels PXL may be located in the display region DA of the substrateSUB. Each of the pixels PXL may be provided as a minimum unit fordisplaying an image. Each of the pixels PXL may include a light emittingelement that emits white light and/or color light. Each pixel PXL mayemit light of one of red, green, and blue colors, but is not limitedthereto. For example, each pixel PXL may emit light of one of cyan,magenta, yellow, and white colors.

The pixels PXL may be arranged in a matrix form including rows extendingin the first direction DR1 and columns extending in the second directionDR2 intersecting the first direction DR1. But the arrangement form ofthe pixels PXL is not particularly limited, and may be arranged invarious forms.

The driving unit may supply signals to each pixel PXL through the lineportion, so that the operation of the pixel PXL may be controlled. InFIG. 1, the line portion is not shown for convenience of explanation.

The driving unit may include a scan driver SDV for providing scansignals to the pixels PXL through scan lines, a light emitting driverEDV for providing light emission control signals to the pixels PXLthrough light emission control lines, a data driver DDV for providingdata signals to the pixels PXL through data lines, and a timingcontroller. The timing controller may control the scan driver SDV, thelight emitting driver EDV, and the data driver DDV.

FIG. 5 is a cross-sectional view illustrating a portion of the displaydevice shown in FIG. 4. In this embodiment of the invention, differencesfrom the above-described embodiment are mainly described in order toavoid redundant description. The parts not specifically described inthis embodiment accord with the above-described embodiment. The samenumerals denote the same constituent elements and similar numeralsdenote similar constituent elements.

Referring to FIGS. 1 to 5, the display device according to an embodimentof the invention may include the substrate SUB, a display element layerDPL provided on the substrate SUB, and a pixel circuit portion PCLprovided on the display element layer DPL.

The substrate SUB may include a transparent insulating material totransmit light. In addition, the substrate SUB may be a rigid substrateor a flexible substrate. The rigid substrate may include a glasssubstrate, a quartz substrate, a glass ceramic substrate, and acrystalline glass substrate. The flexible substrate may include a filmsubstrate including a polymer organic material and a plastic substrate.For example, the flexible substrate may include a material selected fromthe group consisting of polyethersulfone (PES), polyacrylate,polyetherimide (PEI), polyethylene naphthalate (PEN), polyethyleneterephthalate (PET), polyphenylene sulfide (PPS), polyarylate (PAR),polyimide (PI), polycarbonate (PC), triacetate cellulose (TAC), andcellulose acetate propionate (CAP). In addition, the flexible substratemay include fiber glass reinforced plastic (FRP).

The material applied to the substrate SUB may preferably have resistanceor heat resistance to a high processing temperature in the manufacturingprocess of the display device. In an embodiment of the invention, thesubstrate SUB may be entirely or at least partially flexible.

The display element layer DPL may include the buffer layer BFL, therod-like LED LD, the first electrode EL1, the second electrode EL2, thefirst contact electrode CNE1, and the second contact electrode CNE2.

The buffer layer BFL may prevent impurities from diffusing into therod-like LED LD. The buffer layer BFL may be provided as a single layer,but may also be provided as at least two or more layers. When the bufferlayer BFL is provided in multiple layers, each layer may be formed ofthe same material or different materials. The buffer layer BFL may notbe omitted depending on the material of the substrate SUB and theprocess conditions.

The rod-like LED LD may be positioned on the buffer layer BFL. Therod-like LED LD may include a first rod-like LED LD1 and a secondrod-like LED LD2. Each of the first and second rod-like LEDs LD1 and LD2may include the first conductive semiconductor layer 11, the secondconductive semiconductor layer 13, and the active layer 13 positionedbetween the first and second conductive semiconductor layers 11 and 13.In addition, each of the first and second rod-like LEDs LD1 and LD2 mayinclude the first end EP1 and the second end EP2 along the longitudinaldirection. One of the first and second conductive semiconductor layers11 and 13 may be disposed in the first end EP1 and the other one of thefirst and second conductive semiconductor layers 11 and 13 may bedisposed in the second end EP2. Each of the first and second rod-likeLEDs LD1 and LD2 may emit color light and/or white light.

The partition wall PW may be provided on the buffer layer BFL and maypartition a light emitting region of the display device. The partitionwall PW may include openings corresponding to the first and secondrod-like LEDs LD1 and LD2.

The first insulation layer INS1 may be positioned on the buffer layerBFL including the partition wall PW. The first insulation layer INS1 maycover a portion of the top surface of each of the first and secondrod-like LEDs LD1 and LD2. The first and second ends EP1 and EP2 of eachof the first and second rod-like LEDs LD1 and LD2 may be exposed to theoutside by the first insulating layer INS1.

The first electrode EL1 may be disposed on the partition wall PW. Thefirst electrode EU may include the (1-1)th electrode EL1_1 arrangedadjacent to the first end EP1 of the first rod-like LED LD1 and the(1-2)th electrode EL1_2 arranged adjacent to the second end EP2 of thesecond rod-like LED LD2.

The second electrode EL2 may be positioned on the buffer layer BFLbetween the first and second rod-like LEDs LD1 and LD2. One side of thesecond electrode EL2 may be arranged adjacently to the second end EP2 ofthe first rod-like LED LD1 and the other side of the second electrodeEL2 may be arranged adjacent to the first end EP1 of the second rod-likeLED LD2.

The first contact electrode CNE1 for electrically and/or physicallyconnecting the first electrode EL1 and the rod-like LED LD may beprovided on the first electrode EL1. The first contact electrode CNE1may include a transparent conductive material such as ITO (indium tinoxide), IZO (indium zinc oxide), or ITZO (indium tin zinc oxide) so asto transmit light emitted from the rod-like LED LD, but the invention isnot limited thereto.

The first contact electrode CNE1 may include the (1-1)th contactelectrode CNE1_1 provided on the (1-1)th electrode EL1_1 and the (1-2)thcontact electrode CNE1_2 provided on the (1-2)th electrode EL1_2. The(1-1)th contact electrode CNE1_1 may be in ohmic contact with the firstend EP1 of the first rod-like LED LD1 and the (1-2)th contact electrodeCNE1_2 may be in ohmic contact with the second end EP2 of the secondrod-like LED LD2.

The second insulation layer INS2 may be positioned on the substrate SUBincluding the first contact electrode CNE1. The second insulation layerINS2 may be an inorganic insulation layer including an inorganicmaterial or an organic insulation layer including an organic material.The second insulation layer INS2 may cover the first contact electrodeCNE1 and may prevent or reduce corrosion of the first contact electrodeCNE1.

The second contact electrode CNE2 for electrically and/or physicallyconnecting the second electrode EL2 and the first and second rod-likeLEDs LD1 and LD2 may be disposed on the second electrode EL2. The secondcontact electrode CNE2 may include the same material as the firstcontact electrode CNE1, but is not limited thereto.

The second contact electrode CNE2 may cover the one side of the secondelectrode EL2 and the second end EP2 of the first rod-like LED LD1 andmay be connected to the second electrode EL2 and the second end EP2 ofthe first rod-like LED LD1. In addition, the second contact electrodeCNE2 may cover the other side of the electrode EL2 and the first end EP1of the second rod-like LED LD2 and may be connected to the secondelectrode EL2 and the first end EP1 of the second rod-like LED LD2. Oneside of the second contact electrode CNE2 may be in ohmic contact withthe second end EP2 of the first rod-like LED LD1 and the other side ofthe second contact electrode CNE2 may be in ohmic contact with the firstend EP1 of the second rod-like LED LD2.

The third insulation layer INS3 may be positioned on the second contactelectrode CNE2. The third insulation layer INS3 may cover the secondcontact electrode CNE2 positioned under the third insulating layer INS3so as not to be exposed to the outside.

The overcoat layer OC may be positioned on the third insulation layerINS3. The overcoat layer OC may be a planarization layer that serves toflatten the surface roughened by the underlying components. In addition,the overcoat layer OC may be an encapsulating layer that prevents orreduces instances of oxygen and moisture penetrating into the first andsecond rod-like LEDs LD1 and LD2.

The pixel circuit portion PCL may be positioned on the overcoat layerOC. The pixel circuit portion PCL may include a first transistor Ts, asecond transistor Td, a driving voltage line DVL, and a bridge patternBRP.

The first transistor Ts may be a switching transistor electricallyconnected to the second transistor Td to switch the second transistorTd. The second transistor Td may be a driving transistor electricallyconnected to the rod-like LED LD to drive the rod-like LED LD.

Each of the first and second transistors Ts and Td may include asemiconductor layer SCL, a gate electrode GE, a source electrode SE, anda drain electrode DE.

The semiconductor layer SCL may be positioned on the overcoat layer OC.The semiconductor layer SCL may include a source region and a drainregion which are in contact with the source electrode SE and the drainelectrode DE, respectively. The region between the source region and thedrain region may be a channel region. The semiconductor layer SCL may bea semiconductor pattern made of poly silicon, amorphous silicon, oxidesemiconductor, or the like. The channel region may be a semiconductorpattern doped with an impurity. As the impurity, an n-type impurity, ap-type impurity, and other impurities such as metal may be used.

The gate electrode GE may be positioned on the semiconductor layer SCLwith a first gate insulation layer Gil interposed therebetween.

Each of the source electrode SE and the drain electrode DE of the firsttransistor Ts may be connected to the source region and the drain regionof the corresponding semiconductor layer SCL through contact holespassing through an interlayer insulation layer ILD, a second gateinsulation layer GI2, and the first gate insulation layer GI1.

The source electrode SE of the second transistor Td may be connected tothe source region of the corresponding semiconductor layer SCL through acontact hole passing through the interlayer insulation layer ILD, thesecond gate insulation layer GI2, and the first gate insulation layerGI1.

In an embodiment of the invention, the drain electrode DE of the secondtransistor Td may be connected to the drain region of the correspondingsemiconductor layer SCL through a contact hole passing through thesecond gate insulation layer GI2 and the first gate insulation layerGI1. In addition, the drain electrode DE of the second transistor Td maybe connected to the second contact electrode CNE2 by a second openingOPN2 sequentially passing through the second gate insulation layer GI2,the first gate insulation layer GI1, the overcoat layer OC, and thethird insulation layer INS3.

The drain electrode DE of the second transistor Td may include a firstportion DE1 connected to the drain region of the semiconductor layer SCLand a second portion DE2 connected to the second contact electrode CNE2.

The driving voltage line DVL may be positioned on the first gateinsulation layer GI1. A signal corresponding to a driving voltage may besupplied to the driving voltage line DVL from a driving unit.

The bridge pattern BRP may be positioned on the driving voltage line DVLwith the second gate insulation layer GI2 interposed therebetween.

The bridge pattern BRP may be electrically connected to the drivingvoltage line DVL through a contact hole passing through the second gateinsulation layer GI2. In addition, the bridge pattern BRP may beelectrically connected to the (1-1)th contact electrode CNE1_1 by afirst opening OPN1 sequentially passing through the second gateinsulation layer GI2, the first gate insulation layer GI1, the overcoatlayer OC, and the third insulation layer INS3.

In an embodiment of the invention, the bridge pattern BRP may include afirst bridge pattern BRP1 electrically connected to the (1-1)th contactelectrode CNE1_1 and a second bridge pattern BRP2 electrically connectedto the driving voltage line DVL. The first and second bridge patternsBRP1 and BRP2 may be integrally provided and may be electrically andphysically connected to each other. Although not shown in the drawings,the first opening OPN1 may be provided to expose a portion of the(1-2)th contact electrode CNE1_2 in the display device. The bridgepattern BRP may be electrically connected to the (1-2)th contactelectrode CNE1_2 through the first opening OPN1.

The pixel circuit portion PCL may include a passivation layer PSVcovering the first and second transistors Ts and Td. The passivationlayer PSV may include at least one of an inorganic insulation layerincluding an inorganic material and an organic insulation layerincluding an organic material. For example, the passivation layer PSVmay include an inorganic insulation layer and an organic insulationlayer formed on the inorganic insulation layer.

As described above, the drain electrode DE of the second transistor Tdmay be electrically connected to the second contact electrode CNE2disposed below the second transistor Td by the second opening OPN2.Accordingly, the second contact electrode CNE2 may receive a signal fromthe second transistor Td. The signal of the second transistor Tdtransmitted to the second contact electrode CNE2 may be finally appliedto the second end EP2 of the first rod-like LED LD1.

The bridge pattern BRP electrically connected to the driving voltageline DVL may be electrically connected to the (1-1)th contact electrodeCNE1_1 by the first opening OPN1. Therefore, the (1-1)th contactelectrode CNE1_1 may receive a signal from the driving voltage line DVL.The signal transmitted to the (1-1)th contact electrode CNE1_1 may befinally applied to the first end EP1 of the first rod-like LED LD1.

Accordingly, the first rod-like LED LD1 may receive a voltage (e.g., apredetermined voltage) through the (1-1)th contact electrode CNE1_1 andthe second contact electrode CNE2. When an electric field exceeding thevoltage (e.g., the predetermined voltage) is applied to the first andsecond ends EP1 and EP2 of the first rod-like LED LD1, the firstrod-like LED LD1 emits light while the electron-hole pairs are generatedin the active layer 12 of the first rod-like LED LD1.

As described above, the first end EP1 of the second rod-like LED LD2 maycontact the second contact electrode CNE2 and the second end EP2 of thesecond rod-like LED LD2 may contact the (1-2)th contact electrodeCNE1_2. Therefore, the second rod-like LED LD2 may receive a voltage(e.g., a predetermined voltage) through the second contact electrodeCNE2 and the (1-2)th contact electrode CNE1_2. When an electric fieldexceeding the voltage (e.g., the predetermined voltage) is applied tothe first and second ends EP1 and EP2 of the second rod-like LED LD2,the second rod-like LED LD2 emits light while the electron-hole pairsare generated in the active layer 12 of the second rod-like LED LD2.

The display device may further include a polarizing film POL. Thepolarizing film POL may prevent external light from being reflected onthe display device. The polarizing film POL may include a linearpolarizer and a phase difference layer disposed on the linear polarizer.

The polarizing film POL may be positioned on the other surface of thesubstrate SUB on which the display element layer DPL is not provided. Inparticular, when the second contact electrode CNE2 is formed of aconductive material having a high reflectivity, the polarizing film POLmay be positioned on the other surface of the substrate SUB. The secondcontact electrode CNE2 may be formed of a single layer made of Ag, or atriple layer including ITO/Ag/ITO.

When the second contact electrode CNE2 is formed of the conductivematerial having the high reflectivity, light emitted from the rod-likeLED LD may be reflected toward the other surface of the substrate SUB bythe second contact electrode CNE2. Therefore, the display device maydisplay an image toward the other surface of the substrate SUB.

In general, a display device having a normal structure may include astructure in which a substrate, a pixel circuit portion provided on onesurface of the substrate, and a display element layer provided on thepixel circuit portion are sequentially stacked. In particular, in thedisplay device of the normal structure, the polarizing film may beprovided on the overcoat layer of the display element layer. In thedisplay device of the normal structure, the overcoat layer may have acurved surface due to a step difference between the display elementlayer and the pixel circuit portion positioned below the overcoat layer.When the polarizing film is provided on the curved surface of theovercoat layer, the polarizing film may not be fixed on the overcoatlayer and may be partially detached from the overcoat layer. Such thepartial detachment of the polarizing film may be visually recognized asa speckle or a spot, which may lead to poor image quality of the displaydevice.

The display device according to an embodiment of the invention may havethe polarizing film POL directly positioned on the other surface of thesubstrate SUB on which the display element layer DPL and the pixelcircuit portion PCL are not provided. Because the polarizing film POL isprovided directly on the other surface of the substrate SUB having aflat surface, defects of the image quality in the display device of thenormal structure may be minimized.

In the display device of the normal structure, the display element layermay be formed on the substrate after the pixel circuit portion is formedon the substrate. The rod-like LED included in the display element layermay be manufactured by a metal-organic chemical vapor deposition (MOCVD)method in a high temperature condition of 800° C. to 900° C. Thetransistor included in the pixel circuit portion may be influencedduring the manufacturing process of the rod-like LED, and the electricalcharacteristics of the transistor may be changed or malfunctioned. As aresult, the display device may fail to operate.

In the display device according to an embodiment of the invention, thepixel circuit portion PCL may be formed structurally after the displayelement layer DPL is formed. Therefore, since the pixel circuit portionPCL is not affected by the manufacturing process of the display elementlayer DPL, defective driving of the display device may be prevented.

FIGS. 6 to 17 are cross-sectional views sequentially illustrating amethod of manufacturing the display device shown in FIG. 5.

Referring to FIGS. 5 and 6, the buffer layer BFL may be formed on thesubstrate SUB and the partition wall PW may be formed on the bufferlayer BFL. The (1-1)th electrode EL1_1, the (1-2)th electrode EL1_2, andthe second electrode EL2 may be formed on the substrate SUB includingthe partition wall PW. The (1-1)th electrode EL1_1 and the (1-2)thelectrode EL1_2 may be provided on the corresponding partition wall PW.The second electrode EL2 may be provided between the (1-1)th electrodeEL1_1 and the (1-2)th electrode EL1_2.

Referring to FIGS. 5 and 7, the first rod-like LED LD1 may be scatteredon the substrate SUB with an electric field applied between the (1-1)thelectrode EL1_1 and the second electrode EL2. In addition, the secondrod-like LED LD2 may be scattered on the substrate SUB with an electricfield applied between the second electrode EL2 and the (1-2)th electrodeEL1_2.

As a non-limiting example of a method of scattering the first and secondrod-like LEDs LD1 and LD2 on the substrate SUB on which the (1-1)thelectrode EL1_1, the (1-2)th electrode EL1_2, and the second electrodeEL2 are formed, an ink-jet printing method may be used. However, theinvention is not limited thereto.

When the first and second rod-like LEDs LD1 and LD2 are provided, sincethe electric field is formed between the (1-1)th electrode EL1_1 and thesecond electrode EL2 and the electric field is formed between the secondelectrode EL2 and the (1-2)th electrode EL1_2, self-alignments of thescattered first and second rod-like LEDs LD1 and LD2 may be induced.

Referring to FIGS. 5 and 8, an insulating material layer may be coatedon an entire surface of the substrate SUB on which the first and secondrod-like LEDs LD1 and LD2 are aligned, and a mask process or the likemay be performed to form a first insulation pattern INS1′ that coversthe second end EP2 of the first rod-like LED LD1 and the first end EP1of the second rod-like LED LD2. The first end EP1 of the first rod-likeLED LD1 and the second end EP2 of the second rod-like LED LD2 may beexposed to the outside.

Referring to FIGS. 5 and 9, the (1-1)th contact electrode CNE1_1 and the(1-2)th contact electrode CNE1_2 may be formed on the substrate SUBincluding the first insulation pattern INS1′.

The (1-1)th contact electrode CNE1_1 may cover the (1-1)th electrodeEL1_1 and the first end EP1 of the first rod-like LED LD1 and may beelectrically connected to the (1-1)th electrode EL1_1 and the first endEP1 of the first rod-like LED LD1. That is, the (1-1)th contactelectrode CNE1_1 may electrically and/or physically connect the (1-1)thelectrode EL1_1 and the first end EP1 of the first rod-like LED LD1.

The interface between the first end EP1 of the first rod-like LED LD1and the (1-1)th contact electrode CNE1_1 may be heat-treated by a rapidthermal annealing (RTA) process. As a result, the first end EP1 of thefirst rod-like LED LD1 and the (1-1)th contact electrode CNE1_1 may bein ohmic contact with each other.

The (1-2)th contact electrode CNE1_2 may cover the (1-2)th electrodeEL1_2 and the second end EP2 of the second rod-like LED LD2 and may beelectrically connected to the (1-2)th electrode EL1_2 and the second endEP2 of the second rod-like LED LD2. That is, the (1-2)th contactelectrode CNE1_2 may electrically and/or physically connect the (1-2)thelectrode EL1_2 and the second end EP2 of the second rod-like LED LD2.

The interface between the second end EP2 of the second rod-like LED LD2and the (1-2)th contact electrode CNE1_2 may be heat-treated by a rapidthermal annealing (RTA) process. As a result, the second end EP2 of thesecond rod-like LED LD2 and the (1-2)th contact electrode CNE1_2 may bein ohmic contact with each other.

Referring to FIGS. 5 and 10, an insulating material layer may be coatedon an entire surface of the substrate SUB including the (1-1)th contactelectrode CNE1_1 and the (1-2)th contact electrode CNE1_2, and a maskprocess or the like may be performed to form the second insulation layerINS2 exposing the second electrode EL2, the second end EP2 of the firstrod-like LED LD1, and the first end EP1 of the second rod-like LED LD2.The first insulation pattern INS1′ may be patterned together during themask process, so that the first insulation layer INS1 that exposes thesecond end EP2 of the first rod-like LED LD1, the second electrode EL2,and the first end EP1 of the second rod-like LED LD2 may be formed.

Referring to FIGS. 5 and 11, the second contact electrode CNE2 may beformed on the substrate SUB including the second insulation layer INS2.The second contact electrode CNE2 may cover the second electrode EL2,the second end EP2 of the first rod-like LED LD1, and the first end EP1of the second rod-like LED LD2.

The second contact electrode CNE2 may be connected to the second end EP2of the first rod-like LED LD1 and the second electrode EL2 and mayelectrically and/or physically connect the second end EP2 of the firstrod-like LED LD1 and the second electrode EL2. In addition, the secondcontact electrode CNE2 may be connected to the first end EP1 of thesecond rod-like LED LD2 and the second electrode EL2 and may beelectrically and/or physically connect the first end EP1 of the secondrod-like LED LD2 and the second electrode EL2.

The interface between the second end EP2 of the first rod-like LED LD1and the second contact electrode CNE2 may be heat-treated by a rapidthermal annealing (RTA) process. As a result, the second end EP2 of thefirst rod-like LED LD1 and the second contact electrode CNE2 may be inohmic contact with each other. In addition, the interface between thefirst end EP1 of the second rod-like LED LD2 and the second contactelectrode CNE2 may be heat-treated by the rapid thermal annealing (RTA)process. As a result, the first end EP1 of the second rod-like LED LD2and the second contact electrode CNE2 may be in ohmic contact with eachother.

Referring to FIGS. 5 and 12, a third insulating material layer INS3′ maybe formed on an entire surface of the substrate SUB including the secondcontact electrode CNE2. The third insulating material layer INS3′ maycover the second contact electrode CNE2 and may prevent or reducecorrosion of the second contact electrode CNE2.

Next, an overcoat material layer OC′ may be formed on the thirdinsulating material layer INS3′. The overcoat material layer OC′ mayserve to flatten the surface roughened by the components disposed belowthe overcoat material layer OC′. In addition, the overcoat materiallayer OC′ may prevent oxygen and moisture from the outside frompenetrating into the first and second rod-like LEDs LD1 and LD2.

Referring to FIGS. 5 and 13, the semiconductor layers SCL of the firstand second transistors Ts and Td may be formed on the overcoat materiallayer OC′. The semiconductor layers SCL may be semiconductor patternsmade of poly silicon, amorphous silicon, oxide semiconductor, or thelike.

Referring to FIGS. 5 and 14, a first gate insulating material layer maybe formed on an entire surface of the overcoat material layer OC′including the semiconductor layers SCL and the gate electrodes of thefirst and second transistors Ts and Td and the driving voltage line DVLmay be formed on the first gate insulating material layer GI1′.

The gate electrode GE and the driving voltage line DVL may include atleast one selected from the group consisting of aluminum (Al), silver(Ag), tungsten (W), copper (Cu), nickel (Ni), chromium (Cr), molybdenum(Mo), titanium (Ti), platinum (Pt), tantalum (Ta), neodymium (Nd),scandium (Sc), and alloys thereof. The gate electrode GE may beelectrically insulated from the corresponding semiconductor layer SCL bythe first gate insulating material layer GI1′.

Referring to FIGS. 5 and 15, an insulating material layer may be coatedon an entire surface of the first gate insulating material layer GI1′including the gate electrode GE and the driving voltage line DVL, and amask process or the like may be performed to form a second gateinsulating material layer GI2′ that exposes a portion of the drivingvoltage line DVL. The first gate insulating material layer GI1′corresponding to a portion of the (1-1)th contact electrode CNE1_1 and aportion of the second contact electrode CNE2 may be exposed by thesecond gate insulating material layer GI2′ formed by the mask process.In addition, the first gate insulating material layer GI1′ correspondingto a portion of the semiconductor layer SCL of the second transistor Tdmay be exposed by the second gate insulating material layer GI2′.

The first gate insulating material layer GI1′ may be patterned togetherduring the mask process, so that a first gate insulation pattern GI1″that exposes the overcoat material layer OC′ corresponding to theportion of the (1-1)th contact electrode CNE1_1 and the portion of thesecond contact electrode CNE2 may be formed. In addition, a portion ofthe semiconductor layer SCL of the second transistor Td may be exposedby the first gate insulation pattern GI1″.

The overcoat material layer OC′ may be patterned together during themask process, so that the overcoat layer OC that exposes the thirdinsulating material layer INS3′ corresponding to the portion of the(1-1)th contact electrode CNE1_1 and the portion of the second contactelectrode CNE2 may be formed.

The third insulating material layer INS3′ may be patterned togetherduring the mask process, so that the third insulation layer INS3 thatexposes the portion of the (1-1)th contact electrode CNE1_1 and theportion of the second contact electrode CNE2 may be formed.

In an embodiment of the invention, the (1-1)th contact electrode CNE1_1may be exposed to the outside by the first opening OPN1 sequentiallypassing through the second gate insulating material layer GI2′, thefirst gate insulation pattern GI1″, the overcoat layer OC, and the thirdinsulation layer INS3. The second contact electrode CNE2 may be exposedto the outside by the second opening OPN2 sequentially passing throughthe second gate insulating material layer GI2′, the first gateinsulation pattern GI1″, the overcoat layer OC, and the third insulationlayer INS3.

Next, the bridge pattern BRP and the drain electrode DE may be formed onthe second gate insulating material layer GI2′.

The bridge pattern BRP may be electrically connected to the (1-1)thcontact electrode CNE1_1 and the exposed driving voltage line DVL,respectively. The bridge pattern BRP may include the first bridgepattern BRP1 electrically connected to the (1-1)th contact electrodeCNE1_1 through the first opening OPN1 and the second bridge pattern BRP2electrically connected to the driving voltage line DVL. The first bridgepattern BRP1 and the second bridge pattern BRP2 may be integrallyprovided and may be electrically and physically connected to each other.

The drain electrode DE may be connected to the drain region of thesemiconductor layer SCL of the second transistor Td and the secondcontact electrode CNE2, respectively. The drain electrode DE may includethe first portion DE1 electrically connected to the drain region of thesemiconductor layer SCL of the second transistor Td and the secondportion DE2 electrically connected to the second contact electrode CNE2through the second opening OPN2. The first portion DE1 and the secondportion DE2 may be integrally provided and may be electrically andphysically connected to each other.

Referring to FIGS. 5 and 16, an insulating material may be coated on thesecond gate insulating material layer GI2′ including the bridge patternBRP and the drain electrode DE, and a mask process or the like may beperformed to form the interlayer insulation layer ILD that exposes aportion of the second gate insulating material layer GI2′ correspondingto a portion of the semiconductor layer SCL of each of the first andsecond transistors Ts and Td.

The second gate insulating material layer GI2′ may be patterned togetherduring the mask process, so that the second gate insulation layer GI2exposing the portion of the semiconductor layer SCL of each of the firstand second transistors Ts and Td may be formed.

The first gate insulation pattern GI1″ may be patterned together duringthe mask process, so that the first gate insulation layer GI1 exposingthe portion of the semiconductor layer SCL of each of the first andsecond transistors Ts and Td may be formed.

The source and drain electrodes SE and DE of the first transistor Ts andthe source electrode SE of the second transistor Td may be formed on theinterlayer insulation layer ILD.

The source electrode SE of the first transistor Ts may be connected tothe source region of the corresponding semiconductor layer SCL through acontact hole sequentially passing through the interlayer insulationlayer ILD, the second gate insulation layer GI2, and the first gateinsulation layer GI1.

The drain electrode DE of the first transistor Ts may be connected tothe drain region of the corresponding semiconductor layer SCL through acontact hole sequentially passing through the interlayer insulationlayer ILD, the second gate insulation layer GI2, and the first gateinsulation layer GI1.

In addition, the source electrode SE of the second transistor Td may beconnected to the source region of the corresponding semiconductor layerSCL through a contact hole sequentially passing through the interlayerinsulation layer ILD, the second gate insulation layer GI2, and thefirst gate insulation layer GI1.

Referring to FIGS. 5 and 17, the passivation layer PSV may be formed onthe source and drain electrodes SE and DE of the first transistor Ts andthe source electrode SE of the second transistor Td. The passivationlayer PSV may cover the source and drain electrodes SE and DE of thefirst transistor Ts and the source electrode SE of the second transistorTd. In addition, the passivation layer PSV may prevent corrosion of thesource and drain electrodes SE and DE of the first transistor Ts and thesource electrode SE of the second transistor Td.

Next, the polarizing film POL may be provided on the other surface ofthe substrate SUB on which the first and second rod-like LEDs LD1 andLD2 and the first and second transistors Ts and Td are not provided. Thepolarizing film POL may be directly attached to the other surface of thesubstrate SUB which is a flat surface.

FIG. 18 is a cross-sectional view illustrating a display deviceaccording to another embodiment of the invention. In another embodimentof the invention, different points from the above-described embodimentwill be described in order to avoid redundant description. The parts notspecifically described in this embodiment accord with theabove-described embodiment, and the same numerals denote the sameconstituent elements, and similar numerals denote similar constituentelements.

The display device shown in FIG. 18 may be substantially the same as orsimilar to the display device shown in FIG. 5 except that a reflectiveelectrode is further positioned between the substrate and the displayelement layer, and a polarizing film is positioned on the pixel circuitportion.

Referring to FIGS. 5 and 18, the display device according to anotherembodiment of the invention may include the substrate SUB, the displayelement layer DPL positioned on one surface of the substrate SUB, and apixel circuit portion PCL provided on the display element layer DPL.

A reflective electrode REL may be positioned between the substrate SUBand the display element layer DPL. In an embodiment of the invention,the reflective electrode REL may be made of a conductive material havinga high reflectivity. The reflective electrode REL may be provided on thesubstrate SUB corresponding to the first and second rod-like LEDs LD1and LD2, the first and second electrodes EU and EL2, and the first andsecond contact electrodes CNE1 and CNE2 included in the display elementlayer DPL.

The reflective electrode REL may reflect light emitted from the firstand second rod-like LEDs LD1 and LD2 toward the upper surface of thesubstrate SUB. Accordingly, the display device may be realized to have atop emission structure so that the display device displays an image onthe upper surface of the substrate SUB.

In the display device having the above-described structure, thepolarizing film POL may be positioned on the pixel circuit portion PCL.The polarizing film POL may be positioned on the passivation layer PSVof the pixel circuit portion PCL to prevent external light from beingreflected from the display device.

According to an embodiment of the invention, the display device whichcan improve reliability by preventing defects and the method ofmanufacturing the display device may be provided.

The display device according to an embodiment of the invention may beemployed in various electronic devices. For example, the display devicemay be applied to a television, a notebook, a mobile phone, a smartphone, a smart pad (PD), a PMP, a PDA, a navigation device, variouswearable devices such as a smart watch, or the like.

As described above, the optimal embodiments of the invention have beendisclosed through the detailed description and the drawings. It is to beunderstood that the terminology used herein is for the purpose ofdescribing the invention only and is not used to limit the scope of theinvention described in the claims. Therefore, those skilled in the artwill appreciate that various modifications and equivalent embodimentsare possible without departing from the scope of the invention.Accordingly, the true scope of the invention should be determined by thetechnical idea of the appended claims, and their equivalents.

What is claimed is:
 1. A display device comprising: a substrate; adisplay element layer on one surface of the substrate and including atleast one light emitting element emitting light; and a pixel circuitportion on the display element layer and including at least onetransistor electrically connected to the light emitting element, whereinthe display element layer includes: a first electrode on the substrateand electrically connected to one end of the light emitting element; asecond electrode on the substrate and electrically connected to theother end of the light emitting element; and an insulation layer on thesecond electrode to cover the second electrode, and having a firstopening exposing a portion of the second electrode, wherein the displayelement layer is between the substrate and the pixel circuit portion,wherein the at least one transistor is disposed on the insulation layer,and wherein the second electrode is electrically connected to thetransistor through the first opening.